How many CR of undead can a character control with Animate Dead?


The Animate Dead spell allows you to raise and control zombies or skeletons. The number changes with spell level, and a character’s spell slots change as they level up too.

How can do I calculate the maximum number of undead controllable indefinitely with Animate Dead?

Not including items, feats, tricks, just the number/CR of undead per level that a character can control.